Born in Calcutta, Thomas was taken to South Africa when he was six years old. He moved to England in 1967, where he has written, directed and produced 40 major documentaries and dramas. He is also author of a highly-acclaimed biography Rhodes, the Race for Africa.

Thomas's films have taken the top prizes at numerous documentary festivals, including the most prestigious -- the US Emmy Award, the George Foster Peabody Award (twice), the British Academy Award and the Grierson Award for best British Documentary. Two of his documentaries, Twins - The Divided Self and Man and Animal won fourteen international awards between them.

His recent work includes a two-hour documentary The Qur’an (co-produced by Channel 4 and National Geographic), which premiered in the UK on July 14th 2008, and received outstanding notices from both Muslim and non-Muslim reviewers.

His subsequent documentary For Neda won four major awards -- the 2011 Peabody Award, the Documentary of the Year award from the Foreign Press Association, and the Clarion Award for Best Television Documentary from the Association of Women in Communications. Thomas also shared the Foreign Press Association's Journalist of the Year award with his Iranian co-producer, Saeed Kamali Dehghan.

Thomas's two most recent documentaries, Questioning Darwin (HBO) and Secrets of the Vatican (WGBH Frontline) premiered in the United States in February 2014, and received outstanding reviews and ratings. Secrets of the Vatican had the highest overnight viewing figures for a new Frontline documentary since April 2008, and the third largest audience ever on the Frontline website on the day after the broadcast.